Melanomas More Likely to Arise From New Growths Than Existing Moles

Less than one-third of melanomas came from an existing mole.

In a recent study published in the Journal of the American Academy of Dermatology, investigators found that most melanomas appear as new spots rather than arising from existing spots.

Because the prevalence of nevus-associated melanoma varies substantially, investigators sought to determine its incidence and prevalence by performing a systemic review and meta-analysis. Subanalyses that considered age, tumor thickness, and nevus-type classification were also conducted.

After reviewing 38 published studies comprising 20,126 melanomas, the investigators found that 29% of melanomas arose from an existing mole, whereas 71% appeared on the skin as new spots.

Melanomas that arose from existing moles were found to be thinner than other melanomas, indicating a better prognosis for patients whose melanoma was associated with an established mole than those without.

“These results could indicate that patients who monitor their existing moles for suspicious changes could detect melanoma in its early stages, when it’s more treatable, because the disease is more likely to appear as a new growth,” said author Caterina Longo, MD, PhD. “However, it’s important for everyone to familiarize themselves with all the moles on their skin and look for not only changes to those moles, but also any new spots that may appear.”

Melanoma accounts for less than 1% of skin cancer cases, but the vast majority of skin cancer deaths, according to the Skin Cancer Foundation. An estimated 87,000 new cases of invasive melanoma will be diagnosed in the United States in 2017, with approximately 9730 individuals who will die of the disease.

The American Academy of Dermatology (AAD) encourages regular self-examinations of the skin, and any new or suspicious spots should be checked out by dermatologist. Protecting oneself from UV rays by seeking shade, applying sunscreen, and wearing protective clothing is also recommended by the AAD.

“People may think SPF is the only important element of sunscreen selection, but that’s not the case,” said author Roopal V. Kundu, MD, FAAD. “SPF only tells you how much protection a sunscreen provides against UVB rays. To be protected against both UVA and UVB rays, both of which can cause skin cancer, you need to use a broad-spectrum sunscreen.”